Electroplating of nickel



A propylene or pentylene groups.

I 'tural formula 2,937,978 ELECTROPLATING or NICKEL Wennemar Strauss, Dusseldorf-Holtllausen, Alfred Kirstahler, Dusseldorf, Wolfgang Giindel, Dusseldorf- Oberkassel, and Herman Haas, Dusseldorf-Holthausen, Germany, assignors to Dehydag, Deutsche Hydrierwerke G.m.b.H., Dusseldorf, Germany, a corporation of Germany No Drawing. Filed July 26, 1955, Ser. No. 524,616

Claims priority, application Germany Aug. 13, 1954 12 Claims. (Cl. 204-49) This invention relates to an electroplating process, and more particularly to a process of electrodepositing metals from electroplating baths modified with organic sulfonic acids or their salts.

Copending application Ser. No. 442,199, filed July 8, 1954, now Patent No. 2,849,351, describes an electroplating process which employs electroplating baths modified with thioalkane-sulfonic acid compounds having the general structural formula Zr'-SRSO3H or their watersoluble salts, wherein Z is a radical comprising a carbon atom directly attached to two atoms selected from the group consisting of nitrogen, sulfur and oxygen atoms, the carbon atom also directly attached to the terminal sulfur atom of the -SRSO H group, and R represents a bivalent aliphatic radical which may be unsubstituted or may carry other organic substituent groups,

such as ethylene, propylene, alkylpropylene, hydroxy Specific examples of such compounds are the following:

N,N diethyl dithiocarbamic acid n propylester 1- sodium sulfonate 2 mercapto benzothiazol sulfonate S propane 1 sodium Isothiourea-S-propane-l-sodium sulfonate S-phenyl-trichiocarbonic acid-l-propane-l-sodium sulfonate ISothiourea-S-butane-I-sodium sulfonate N,N pentamethylene dithiocarbamic acid n propylester-l-sodium sulfonat'e N,N-dimethyl-dithiocarbamic acid-n-propylester-l-sodium sulfonate I and the like.

or their water-soluble salts, wherein X represents a halogen, cyano or thiocyanate radical and R represents an aliphatic, cycloaliphatic or aromatic radical which may carry further substituent groups. Specific examples of such compounds are the following:

S-bromopropane-l-sodium sulfonate 4-iodobutane-l-sodium sulfonate 2-bromoethane-1-sodium sulfonate 4-bromobenzene-sodium sulfonate 3-chloropropane-1-sodium sulfonate 3-thiocyanopropane-1-sodium sulfonate 4-thiocyanobutane-1-sodium sulfonate and the like.

We have found that the characteristics of metal electrodeposits can be improved to an unexpected and surprising degree if the electroplating bath is modified with 2,937,978 Patented May 24, 19 60 2 both of the above-described compounds simultaneously. Metal electrodeposits produced from electroplating baths containing both types of sulfonic acid compounds are characterized by considerably greater brightness, much improved distribution of the metal deposit, complete freedom from porosity and absolute uniformity. The high quality metal electrodeposits obtained inthis manner can not be produced with electroplating baths modified with only one of the sulfonic acid compounds as disclosed in said copending applications, nor could it have been expected that a combination of these additives in the same electroplating bath would improve the deposits to the degree that it does.

The amounts in which these sulfonic acid compounds are added to the electroplating bath to produce the improved electrodeposits in accordance with the present invention depend largely upon the composition of the bath and the operating conditions, but they generally range between 0.01 and 20 gm. per liter of bath. The temperature range within which such modified baths may be employed with satisfactory results is between 15 and 65 C. The pH- value of the bath may vary between 3.8 and 4.5, and the current density may vary between 0.5 and 12 amp./dm. v

The electroplating baths modified with the two types of sulfonic acid compounds in accordance with this inagents, smoothing agents and wetting agents.

examplesgiven below. V

vention, i.e. simultaneously with the thioalkane sulfonic acid derivatives and the halogen-, cyanoor thiocyanosubstituted organic sulfonic acids, may be further modified with known brightening agents, porosity-preventing For example, known brightening agents which we have found to be particularly advantageous include polyvalent alcohols such as ethylene-glycol, butanediols, glycerin, erythrite, pentaerythrite, sorbitol, sugars, dior trialkanolamines, also unsaturated alcohols such as butinediol, and furthermore derivatives of polyvalent alcohols which still contain free hydroxyl groups, such as etheralcohols and the like.

Wetting agents which may be advantageously added to the electroplating baths according to ourinvention are, for example, water-soluble salts of alkylsulfonic acids, alkylarylsulfonic acids, and alkylsulfuric acid esters, or water-soluble ethyleneoxide addition products of fatty alcohols, fatty acids, amines and the like.

In some instances it is also advantageous to add to the electroplating baths inorganic brightening agents in small amounts, such as salts of Zinc,.cadmium or cobalt.

Metals upon which electrodeposits may be applied with the aid of the baths modified in accordance with the present invention include all those which are ordinarily used for this purpose, such as, for example, iron, steel,izinc and aluminum, metal alloys such as brass, and other suitable non-precious metals.

All common types of electroplating baths maybe modified with the sulfonic acid compounds above-disclosed, particularly nickel-plating, copper-plating, zinc-plating, silver-plating and other like electroplating baths.

The following examples will further illustrate our invention and enable others skilled in the art to understand the inventionmore completely. It; is understood, however, that we do not wish to limit our invention to the Example I nickel-plated in this bath at a temperature of 45? C. and

deposit produced thereby was of mirror-like brightness and firmly adhered to the iron surfaces of the objects.

.Thebrightness and adhering qualities of the nickel deposit produced in this manner were far superior to .de-

posits produced from similarnickelbaths under similar COIldltlOIlS of temperature andcurrent density, but modified with only one of the above sulfonic acid compounds. Example II A nickel-plating hath containing 400 gm. per liter nickel sulfate, 50 gm. per liter nickel chloride and 35 gm.

, per liter boricacid was modifiedbyadding 10 gm. per

. liter isothiourea-S-propane-l sodium sulfonate and 5 gm.

per liter of glycerin. Sheet steel was .then electroplated in this bath. The nickel elec-trodeposit produced thereby was of exceptionally. high brightness and had excellent adhering qualities and ductility.

Example III I V A nickel-plat ing bath as described in Example I was modified with 5 gm. per liter 4-iodo-butane-l-sodium sul- I fon'ate, 0.5 gm. per liter ethylenethiourea-S-propane-1- sodium sulfonate and 1 gm. per liter butinediol-1,4.

: Copper objects which were electroplated in this bath were provided with a nickel plate which was completely free from pores and extremely bright.

Example IV A nickel-plating bath as described in Example Ilwas modified with 6' gm. per liter of2-bromo-ethanc-sodium sulfonate, 0.2 gml'per' liter isothiourea-S-p'ropane-l-so- "dlum' sulfonate' and 8 gm. perliter triethanolamine. Metal objects electroplated in this bath were provided with "smooth, extremely bright'nickel deposits,v which ad- ,hered excellently to the metal base and were completely free from pores and uniformly distributed over the entire' surface. H

Example V The nickel-plating bathsi described in Examples I and II were modified by dissolving therein 6 gm. per liter of 4-thiocyano-butaue-l-sodium sulfonate,'0.2 gm. per liter isothiourea-S-propane-l-sodium sulfonate and 10 gm. per liter glucose. Iron objects electroplated in these baths were provided with a nickel plate of exceptionally high brightness and smoothness.

While we have given certain specific examples of our invention, we wish it to be understood that the invention is not limited to these examples and that various changes and modifications may be made therein without departin'g'from the spirit of our invention or'thescope of their water-soluble salts, wherein X is selected from the group. consisting of halogen, cyanide and thiocyanide radicals, and Ris an aliphatic radical with from 2 to 4 carbon atoms, and about 0.01 to 20 g. per liter of a compound selected from the group consisting of organic sulfonic acids having the general structural formula "z-s-ut-sont iiiiatei''c'illible saltslwh'er'ein is a ing a carbon atom directly attached to two atoms se- {looted from the group conslstin'g or "nitrogen, oxygen and and R is a bivalent aliphatic radical with irom 3 to 4 carbon atoms.

2. A nickel electroplating bath for producing bright, non-porous nickel deposits, comprising an acid solution of inorganic nickel salts and, as brightening agents, 4 g. per liter of S-chIorOprOpane-I-sodinm sulfonate and l g. per liter of isothiourea-S-propane-l-sodium sulfonate.

3. A nickel electroplating bath for producing bright, non-porous nickel deposits, comprising an acid solution of inorganic nickel salts and, as brightening agents, 10 g. per liter of 3-bromopropane-l-sodium sultonate, 0.2 g. per liter of isothiourea-S-propane l-sodium s'ulfonat'e and S g. per liter of glycerin.

4. A nickel electroplating bath for producing bright, non-porous nickel deposits, comprisingan acid solution of inorganic nickel salts and, as brightening agents, 5 g. per liter of 4-iodobutane l-sodium sulfonate, 0.5 g. per liter of ethylenethiourea-S-propane-l-sodium sulfonate and l g. per liter of butinediol-l,4.

5. A nickel electroplating bath for producing bright, non-porous nickel deposits, comprising an acid, solution of inorganic nickel salts and, as brightening agents, 2 g. per liter of Z-bromoethane-l-sodium sulfonate, 0.2 g. per liter of isothiourea-S-propane-l-sodium sulfonate and 8 g. per liter of triethanolamine.

6..A nickel electroplating bath for producing bright,

. non-porous. nickel deposits, comprising an acid solution .of.inorganic nickel salts and, as brightening agents, 6 g.

. per liter of 4-thiocyanobutane-1-sodium sulfonate, 0.2 g.

per liter of isothiourea-S-propane-l-sodium sulfonate and 10 g. per liter of glucose.

v 7. The process of producing bright, non-porousnickel electrodeposits, which comprises electrodepositing said nickel from abath containing said nickel principally inv the form of an acid solution of an inorganic salt of the nickel in the presence offltwobrightening agents, one selected from the group consisting of organic sulfonic acids having the general structural formula and their" water-soluble salts, said"compounds being halogen, cyanide and thiocyanide radicals, and R is'an aliphatic radical with frorn2 to 4 carbon atoms, the

. other selected from the group consisting of organic sulfonic acids having the general structural formula ZSRSO H and their water-soluble salts, said compounds being present in an amount of about 0.01 to 20 g. per liter,

Iwh'erein Z is a radical comprising a carbon atom directly I attached to two atoms selected from the group consisting of nitrogen, sulfur and oxygen atoms, sald carbon atom'also directly attached to the terminal sulfur atom of the -SRSO H gr up, and R is a bivalentaliphatic radical with from 3 to 4 carbon atoms.

.8. The process of producing bright, non-porous nickel electrodeposits, which comprises.electrodepositing said nickel from. a bath containing said nickelprincipally in the form of an acid solution of an inorganicnickel salt in the presence. of 4 g. per liter of 3-chloropropanel-sodium sulfonate and '1 g'. per liter of isothiourea-S- propane-l-sodium sulfonate as brightening. agents.

9. The process of producing bright,,non.-porous nickel electrodeposits,.which comprises .electrodepositing said nickel from a .bathcontainingsaidnickel principally in the form ofan acid solutionof aninorganic nickel salt in thepre'sence of 10 g. perliter of 3-,bromopropanel-sodium s'ulfonate, 0.2 g. per. liter .of. isothionrea-S- propane-l-sodium sulfonate and 5 g. per liter of glycerin as brightening agents. 7 10. "The process of producing bright, non-porous nickel iblectrodeposits', fwhich comprises eiearodepesiang said "nickel from a bath' containing said nickelprincipally assays-1e in the form on an acid solution of an inorganic nickel salt in the presence of 5 g. per liter of 4-iodobutane-1- sodium sulfonate, 0.5 g. per liter of ethylenethiourea- S-propane-l-sodium sulfonate and 1 g. per liter of butinediol-1,4, as brightening agents.

11. The process of producing bright, non-porous nickel electrodeposits, which comprises electrodepositing said nickel from a bath containing said nickel principally in the form of an acid solution of an inorganic nickel salt in the presence of 2 g. per liter of 2-bromoethanel-sodium sulfonate, 0.2 g. per liter of isothiourea-S- propane-l-sodium sulfonate and 8 g. per liter of triethanolamine, as brightening agents.

12. The process of producing bright, non-porous nickel electrodeposits, which comprises electrodepositing said References Cited in the file of this patent UNITED STATES PATENTS 1,524,448 Murphy Jan. 27, 1925 1,642,238 Gardner Sept. 13, 1927 2,647,866 Brown Aug. 4, 1953 2,648,627 Donnelly Aug. 11, 1953 UNITED STATES PATENT OFFICE CERTIFICATE GF CORRECTION Patent No 2 937 978 May 24 1960 Wennemar vStrauss et al It is hereby certified that error appears in the-printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 4:0 for d'trichiocarbonic", read trithiocarbonic column 5 line 1, for "on". read of Signed and sealed this 29th day of November 1960;,

(SEAL) Attest:

KARL Ho AXLINE ROBERT C. WATSON Attesting Officer Commissioner of Patents 

1. AN ELECTROPLATING BATH FOR PRODUCING BRIGHT, NONPOROUS NICKEL DEPOSITS, COMPRISING AN ACID SOLUTION OF AN INORGANIC SALT OF NICKEL AND, AS BRIGHTENING AGENTS, ABOUT 0.01 TO 20 G. PER LITER OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF ORGANIC SULFONIC ACIDS HAVING THE GENERAL STRUCTURAL FORMULA 